Blower for Motor Vehicle

ABSTRACT

posed is a blower ( 10 ) for a motor vehicle, in particular a blower ( 10 ) for a heating and air conditioning unit and/or an engine of a motor vehicle, comprising:—a compressed air generator ( 14 ) for generating compressed air and—a sheath flow nozzle ( 12 ) for discharging the compressed air in the form of a sheath flow ( 34, 34   a,    34   b,    34   c ) by means of which feed air ( 32 ), in particular feed air conducted to the sheath flow nozzle ( 12 ) via a feed air supply ( 20 ), is entrained in the form of a central flow ( 36, 36   a,    36   b,    36   c ).

The present invention relates to a blower for a motor vehicle, in particular a blower for a heating and air conditioning unit and/or an engine of a motor vehicle. The engine further relates to a method for ventilating a motor vehicle as well as to an assembly consisting of a blower and a heat exchanger for a motor vehicle.

Automotive blowers are used, for example, in the radiator. Typically, a fan with rotating rotor blades is provided and conducts outdoor air to cool the engine water and/or the condenser of the air conditioning unit. The air heated in this way can be used simultaneously for heating the vehicle cabin. In the case of such fans, in the prior art an asymmetric division of the rotors as well as an optimised flow profile of the rotor blades are used. However, in the prior art there is a problem that such blowers produce significant noise during operation, which is perceived in the vehicle cabin as unpleasant. Another problem is that the large rotor blades accumulate dirt over time and are difficult to clean from the outside. In this respect, it cannot always be ensured that, for example, the engine water or the condenser of the refrigeration circuit are sufficiently cooled.

In view of the above problems in the prior art, the purpose of the present invention is to provide a blower and a method for ventilating a vehicle in which one or more of the aforementioned problems do not occur.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention a blower for a motor vehicle, in particular for a heating and air conditioning unit and/or an engine of a motor vehicle, is provided, wherein the blower comprises:

-   -   a compressed air generator for generating compressed air and     -   a sheath flow nozzle for discharging the compressed air in the         form of a sheath flow, by means of which feed air, in particular         feed air conducted to the sheath flow nozzle via a feed air         supply, is entrained in the form of a central flow.

A further aspect of the invention relates to a method for ventilating a motor vehicle, in particular for ventilating a heating and air conditioning unit and/or an engine of a motor vehicle, comprising the following steps:

-   -   generating compressed air     -   conducting the compressed air to a nozzle,     -   discharging the compressed air from the nozzle in the form of a         sheath flow, and     -   entraining feed air as a central flow within the sheath flow.

Preferred embodiments of the invention are defined in the dependent claims.

The blower according to the invention can, for example, be used as a passenger car front fan, which cools the cooler of the engine water and/or the condenser of the air conditioning unit. According to the invention, it is possible for most of the feed air to be discharged from the blower as a central flow, in which case the central flow is not driven by rotor blades but is entrained by the sheath flow. Experiments have shown that the acceleration of the air by rotor blades is responsible for much of the noise that is produced, whereas the entrainment of the central flow according to the invention causes the development of much less noise. A specific quantity of accelerated sheath flow can cause a multiple volume of air to be entrained as a central flow. A similar principle has proven to be very efficient, for example in the Dyson fan or jet engines.

It is understood that, in this case, not only does the sheath flow nozzle have a point-shaped opening but the opening according to the invention is typically designed in a linear fashion or in a linear fashion with breaks, so that a suitable sheath flow for entraining the central flow can be generated. The contour of the sheath flow nozzle does not have to be closed. It is also possible for open line sections to be provided. A possible lower fluidic efficiency is taken into account.

The blower according to the invention essentially does not require rotor blades. The compressed air generator can be executed in the form of a compressor, in which case, in certain embodiments, rotor blades are used in the compressor. Since the compressor is advantageously only used for the generation of the compressed air for the sheath flow, many of the disadvantages of the use of rotor blades can nevertheless be avoided, because the rotor blades in the compressor are much smaller than the main rotor blades in a conventional blower.

Typically, the compressed air generator is a compressor or a similar device, which is supplied with energy by an electric current or (indirectly) by a petrol engine. However, according to the invention it is also conceivable that, when the vehicle is travelling at high speed, compressed air for generating the sheath flow is generated from the airstream.

The central flow can, as usual, be conducted over a heat exchanger or evaporator of the air conditioning unit, supplied by external air or air circulating in the vehicle cabin as feed air. In other embodiments of the invention the feed air can also be partially or completely conducted out of the indoor air of the vehicle cabin.

The feed air supply can supply feed air from outside the motor vehicle. The feed air supply can also conduct air to the compressed air generator. In other embodiments of the invention, the compressed air generator is supplied with air separately.

According to a preferred embodiment of the invention, it is provided that the compressed air of the sheath flow nozzle is conducted from the compressed air generator through a duct with a sound attenuator, in particular a pipe silencer.

Through vibrations of the compressed air generator, for example a compressor, and through the high pressure and high velocity of the air accelerated by the compressed air generator, the conduction of the compressed air can give rise to the development of noise, which can be counteracted by the sound attenuator.

According to a further embodiment of the invention, it is provided that the feed air supply comprises a first duct, in particular a first pipe or a first hose, and the compressed air is conducted to the sheath flow nozzle through a second duct, in particular a second pipe or a second hose, the second duct being, at least partially, arranged inside the first duct.

It is therefore possible that only one duct is laid in the vehicle; nevertheless, a multiplication of the moved volume of air is possible according to the invention.

According to a further embodiment of the invention, it is provided that the discharge opening of the sheath flow nozzle has an oval, in particular a circular, or a rectangular contour.

According to a further embodiment of the invention, it is provided that the discharge opening is designed as a gap between two essentially parallel surfaces, in particular the discharge opening being broken up by spacers arranged between the parallel surfaces.

The discharge opening can therefore be designed in the form of a discharge gap. The essentially parallel surfaces of the sheath flow nozzle are designed completely parallel or they can, in other embodiments of the invention, be arranged in parallel or deviating from the parallelism by no more than +/−3°. The discharge opening can have spacers, which stabilise the parallel surfaces relative to each other, so that, even in the event of high pressures, the stability of the arrangement is guaranteed.

According to a further embodiment of the invention, it is provided that, in the direction of discharge, behind the discharge opening, a wall, in particular a wall oriented parallel to the direction of discharge, is arranged, on the surface of which the sheath flow moves along.

According to this embodiment, as a consequence of the Coanda effect, the sheath flow can be attracted by the wall of the sheath flow nozzle and flow along the wall. This enables a particularly even sheath flow to be achieved. This results in, among other things, a particularly low noise level.

According to a further embodiment of the invention, it is provided that the sheath flow nozzle is arranged such that the sheath flow is directed at particularly heated points in the engine compartment, in particular an exhaust manifold or a turbocharger.

The turbocharger can be cooled by a supply flow and a sheath flow supplied by charge air. A special control (for example via valves) is unnecessary, because the cooling requirement of the turbocharger involves available charge air. Through oil separation between charge air and sheath flow connection, it must be ensured that no droplets of oil fall onto the hot turbocharger housing.

With the blower according to the invention a targeted reduction of operating temperatures at critical points in the engine compartment can therefore be carried out. Several blowers according to the invention can also be combined at critical points in the engine compartment, which allows the supply of compressed air to the individual sheath flow nozzles to be controlled individually. The sheath flow and the entrained central flow can therefore by adapted to the cooling capacity required in each case.

According to a further embodiment of the invention, it is provided that the blower has at least a first sheath flow nozzle for discharging the compressed air in the form of a first sheath flow, which entrains a first central flow, and at least a second sheath flow nozzle for discharging the compressed air in the form of a second sheath flow, with the second sheath flow entraining the first central flow entrained by the sheath flow of the first sheath flow nozzle.

When the sheath flow direction is aligned (for example in the rearwards direction of travel), its effect is added, with the result that the external air mass flow to the supplied point is increased. The first and the at least second sheath flow nozzle can be supplied via the compressed air generator or several compressed air generators can be provided, which supply the individual sheath flow nozzles separately with compressed air.

Sheath flow nozzles with a driving sheath flow can, according to the invention, also be used for extraction—combinable with supply air nozzles without a driving sheath flow.

Connecting several sheath flow nozzles in series can be useful, for example in the heating and air conditioning unit, where a significant fall in pressure sometimes occurs along the, at times, longer paths of the actual supply air, which reduces the desired sheath flow. Through the multi-level connection in series of sheath flow nozzles, which are distributed over the length of the air ducts, the pressure differences impacting on the central flow are added together. Several sound attenuators can be used. The sound attenuator effect can be achieved, for example, through microperforated surfaces, which do not require any defined absorber material.

According to a further embodiment of the invention, it is provided that the sheath flow nozzle has several nozzle areas for the generation of several individual sheath flows, and the pressures of the individual sheath flows can be controlled individually.

The orientation of the total flow (consisting of the individual sheath flow and the entrained individual central flows) can be controlled in a targeted manner through the suitable control of the pressures of the individual sheath flows. This means that mechanical louvers can be dispensed with and a continuous adjustment of the overall emittance direction is still possible. A temporal variance of the individual sheath flows can support comfort-oriented ventilation concepts that supplement static flow conditions through occasional stronger air flows directed at the vehicle occupants, for example, with somewhat cooler air.

The radiation direction of the sheath flow nozzle can be controlled like an adjustable louver, if the individual sections of the nozzle contour receive different sheath flow strengths. Temporal variation enables comfort programmes of the cabin air conditioning to be presented (for example, palm frond effects of an occasionally cooler flow to the vehicle occupants, without causing health risks through stationary flow, such as muscle tension).

According to a further embodiment of the invention, it is provided that the sheath flow nozzles have a maximum diameter of between 10 and 100 cm, in particular between 25 and 75 cm, and/or the discharge opening has a length of between 50 and 200 cm and a width of between 1 mm and 20 mm, in particular between 2 mm and 10 mm.

In an elliptical shape, for example, the maximum diameter is to be regarded as the length of the longer half axis.

Particularly efficient ventilation can be achieved in the engine compartment with these dimensions of the sheath flow nozzle. In particular, it has been shown that a particularly high velocity of the discharged sheath flow can be achieved with a comparatively thin discharge opening and, therefore, the central flow can be speeded up to a particularly high level.

In a further embodiment of the method according to the invention, it is provided that the volume flow of the central flow is at least 5 times as large, in particular at least 10 times as large, as the volume flow of the sheath flow.

In a further embodiment of the method according to the invention, it is provided that the blower is arranged in the direction of travel of the motor vehicle directly in front of and/or directly behind the heat exchanger.

In a further embodiment of the method according to the invention, it is provided that the first sheath flow nozzle of the blower is arranged on one side of the heat exchanger and the second sheath flow nozzle of the blower is arranged on the other side of the heat exchanger.

Such an arrangement enables maximum ventilation of the heat exchanger. If the sheath flows of both sheath flow nozzles are aligned (e.g. in the rearwards direction of travel) its effect is added, with the result that the external air mass flow to the heat exchangers is increased.

It is understood that the aforementioned features and the features yet to be explained below can be used not only in the stated combination but also in other combinations or in isolation, without stepping outside the framework of the present invention.

Examples for carrying out the invention are shown in the drawings and explained in more detail in the following description.

FIG. 1 is a schematic representation of a blower according to the invention.

FIG. 2 is a schematic representation of a cross section of a duct according to the invention for a central flow and a sheath flow, which are supplied to a sheath flow nozzle.

FIGS. 3A to 3C are schematic representation of the contours of the various sheath flow nozzles according to the invention.

The blower 10 schematically represented in FIG. 1 comprises a sheath flow nozzle 12, a compressed air generator 14 in the form of a compressor and a central feed air supply 20 in the form of a first duct. The compressor 14 is connected to the sheath flow nozzle 12 via a second duct 22. A circular silencer 16 is provided on part of the connecting section between the compressor 14 and the sheath flow nozzle 12.

The compressor 14 sucks in a first air flow 30, compresses it and conducts it through the duct 22 of the sheath flow nozzle to form the sheath flow 34. The sheath flow 34 is discharged at high speed over the entire contour of the sheath flow nozzle 12. In this way, the feed air 32 is entrained with the sheath flow 34 generated in the sheath flow nozzle 12 and discharged as an accelerated central flow 36.

In the embodiment of the invention represented in FIG. 1, the central flow is conducted over a longer duct 20. In other embodiments of the invention no such duct is provided, that is, the sheath flow nozzle 12 draws its feed air 32 directly out of the vehicle's ambient air. In this case a protective guard (not shown in FIG. 1) can be provided to prevent dirt and other unwanted items from getting into the vehicle.

FIG. 2 shows the cross section of a duct 40 of a blower according to a second embodiment of the invention. The duct 40 serves to supply feed air for the central flow. In addition, a thinner duct 42 is arranged in the duct 40 to conduct the compressed air for the sheath flow. Both the duct 40 and the inner duct 42 can be designed as a rigid pipe or a flexible hose. Due to the increased pressure of the compressed air supplied in the inner duct 42, the inner duct preferably has special stability, created for example by an increased hose thickness.

FIG. 3A shows a sheath flow nozzle with a closed oval contour. The generated sheath flow 34 a therefore also has a closed oval contour. The central flow 36 a is entrained inside the sheath flow 34 a.

FIG. 3B shows a sheath flow nozzle with an oval contour, which is broken up by breaks 35. The generated sheath flow 34 b therefore has a discontinuous oval contour. A central flow 36 b with an oval external counter is entrained inside the sheath flow 34 b.

Typically, according to the invention, a central flow is entrained, which is conducted inside the sheath flow. However, as shown in FIG. 3C, embodiments are also conceivable in which the central flow is not conducted inside the sheath flow. For example, FIG. 3C shows a sheath flow nozzle in which linear openings of the nozzle generate the sheath flow 34 c, which entrain a central flow 36 c, which is conducted partly inside and partly outside the central flow. In other embodiments of the invention, different combinations of linear or point-shaped openings of the sheath flow nozzle can be provided.

REFERENCE CHARACTERS: 10 Blower

12 Sheath flow nozzle

14 Compressor

16 Circular silencer 20 First duct 22 Second duct 30 Air flow

32 Feed air

34, 34 a, 34 b, 34 c Sheath flow

35 Break

36, 36 a, 36 b, 36 c Central flow

40 Duct

42 Inner duct 

1. A blower for a motor vehicle, for a heating and air conditioning unit and/or an engine of a motor vehicle, comprising; a compressed air generator for generating compressed air; and a sheath flow nozzle for discharging the compressed air in the form of a sheath flow in which feed air conducted to the sheath flow nozzle via a feed air supply, is entrained in the form of a central flow.
 2. The blower according to claim 1, wherein the compressed air of the sheath flow nozzle is conducted by the compressed air generator through a duct with a sound attenuator comprising a circular silencer.
 3. The blower according to claim 1, wherein the feed air supply comprises a first duct comprising a first pipe or a first hose, and the compressed air is conducted to the sheath flow nozzle through a second duct, comprising a second pipe or a second hose, the second duct being, at least partially, arranged inside the first duct
 4. The blower according to claim 1, wherein the sheath flow nozzle has a discharge opening with an oval comprising a circular, or a rectangular contour.
 5. The blower according to claim 1, wherein the sheath flow nozzle has a discharge opening, which is designed as a gap between two essentially parallel surfaces, wherein the discharge opening is broken up by spacers arranged between the parallel surfaces.
 6. The blower according to claim 4, wherein in the direction of discharge, behind the discharge opening, a wall oriented parallel to the direction of discharge is arranged on the surface of which the sheath flow moves along.
 7. The blower according to claim 1, wherein the sheath flow nozzle comprises the sheath flow nozzle is arranged such that the sheath flow is directed at particularly heated points in an engine compartment comprising an exhaust manifold or a turbocharger.
 8. The blower according to claim 1, wherein the sheath flow nozzle comprises at least one first sheath flow nozzle for discharging the compressed air as a first sheath flow, which entrains a first central flow, and at least a second sheath flow nozzle for discharging the compressed air as a second sheath flow, wherein the second sheath flow entrains the first central flow entrained by the first sheath flow.
 9. The blower according to claim 1, wherein the sheath flow nozzle has several nozzle areas for the generation of several individual sheath flows, wherein the pressures of the individual sheath flows can be controlled individually.
 10. The blower according to claim 1, wherein the sheath flow nozzle has a discharge opening having a maximum diameter of between 10 and 100 cm and/or the discharge opening has a length of between 50 and 200 cm and a width of between 1 mm and 20 mm.
 11. A method for ventilating a motor vehicle, in particular for ventilating a heating and air conditioning unit and/or an engine of a motor vehicle, comprising the following steps: generating compressed air, conducting the compressed air to a sheath flow nozzle, discharging the compressed air from the sheath flow nozzle in the form of a sheath flow, and entraining feed air as a central flow within the sheath flow.
 12. The method according to claim 11, a volume of flow of the central flow is at least 5 times as large as a volume flow of the sheath flow.
 13. The method according to claim 11, wherein as a consequence of a Coanda effect, the sheath flow can be attracted by a wall of the sheath flow nozzle and flow along the wall.
 14. A system comprising a blower according to claim 1 and a heat exchanger of a motor vehicle, wherein the blower is arranged in the direction of travel of the motor vehicle directly in front of and/or directly behind the heat exchanger.
 15. A system comprising a blower according to claim 8 and a heat exchanger of a motor vehicle, wherein the first sheath flow nozzle of the blower is arranged on one side of the heat exchanger and the second sheath flow nozzle of the blower is arranged on the other side of the heat exchanger. 